In some rotary balers presently available the application of compressive forces to the bale during its formation is carried out by two separate structures under the influence of two separate biasing means. For example, flexible belting may be utilized to partially envelope the bale and thus serve as one of the mentioned structures. Additionally, a rigid grid or the like might be employed to encompass yet another part of the bale, the grid swinging to a position effectively enlarging the chamber as the bale grows and the belts likewise being paid out by a slack-control unit as the bale grows to also contribute to enlargement of the bale chamber.
In having such two separate yet cooperating strucutres, it sometimes becomes difficult to properly maintain a balanced application of compressive forces to the bale. That is, the force from the grid might tend to become greater than the force from the belts or vice versa, in which event the bale might tend to take on a transversely elliptical configuration as opposed to the desired transversely circular shape.
Furthermore, the use of two separate systems in this manner necessitates greater material costs and other attendant expenses which would desirably be reduced without sacrificing quality of the finished bale or ease of operation.
Additionally, it has been found that it is most desirable to provide for adjustment of the compacting or compressing force applied to the bale during its formation since varying conditions such as moisture levels, types of crops being harvested, and climate have a direct effect upon the nature of the bale produced by the machine. For example, when harvesting an alfalfa crop, the moisture level in the crop and the nature of the crop itself is normally such that a dense, relatively heavy bale can be produced with perhaps lighter-than-usual tension on the forming belts, but on the other hand, if light prairie grasses are being harvested, the operator normally needs considerably greater compressive forces on the belts throughout the major part of the cycle.
By the same token, however, adjustment in the tension applied to the forming belts is desirably such that the amount of tension on the belts when the chamber is empty at the beginning of the cycle is not adversely affected one way or the other. Still further, if adjustments of this type are to be made, it is imperative that they be capable of being carried out with speed and ease for many reasons known by those skilled in the art.